In this research, ZnO nanoparticles are doped with the manganese (Mn) and gadolinium (Gd) ions using chemical co-precipitation method. The effects of dopants on the structural, morphological and optical properties of ZnO are investigated. In addition, the antimicrobial activity of ZnO nanoparticles doped with the Mn and Gd metallic ions are revealed. The structural, morphological and optical properties are characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM) and ultravioletvisible (UV-Vis) spectroscopy. The XRD results reveal the synthesized nanoparticles possessed hexagonal phase of wurtzite structure and average crystallite size of 31-38 nm. The decreases in crystallite size, lattice parameters, unit volume and bond length are observed after incorporation of the Mn and Gd ions into the ZnO matrix. On the other hand, increments in strain and concentration of defects are observed after the Mn and Gd doping. Scanning electron-microscopy images show spherical shape with well-defined distributions observed. The energy band gaps estimated from ultraviolet-visible absorption spectra are found to be 3.35, 3.28 and 3.07 eV for undoped ZnO, Gd-doped and Mn-doped ones, respectively. The antimicrobial activity of undoped, Mn-and Gd-doped ZnO nanoparticles are tested against gram-negative bacteria (E. coli and P. aeruginosa), grampositive bacteria (S. aureus and B. subtilis) and fungus (C. albicans) using agar-well diffusion method. The results indicate that the antimicrobial activity of doped ZnO nanoparticles is higher as compared to undoped ZnO nanoparticles. As also found, the gram-positive bacteria are more susceptible to ZnO nanoparticle than gram-negative bacteria and fungus.У цьому дослідженні наночастинки ZnO леґуються йонами Манґану (Mn) та Ґадолінію (Gd) за допомогою хемічного методу співосадження. Досліджено вплив леґування на структурні, морфологічні й оптичні властивості ZnO. Крім того, виявлено антимікробну активність наночастинок ZnO, леґованих металічними йонами Mn і Gd. Структурні, мор-